Energy Efficient Upgrades for Renovations: 10 Ways to Improve Your Home’s Performance

If you’re undertaking a renovation project, chances are you’re looking to improve the home’s energy efficiency and incorporate features such as solar panels and heat pumps, alongside upgrading the build’s insulation. To set you off on the right foot, here Opinder Liddar shares 10 efficient upgrades to make during your home renovation

by Opinder Liddar

24th May 2024

If you want to extend and upgrade your home to add space and improve how the building works around you, you’re likely to have energy efficiency as one of your top priorities.

Ever increasing prices and widespread awareness of the need for sustainable living has made many of us ask what we can do to help lower our ongoing costs and reduce our carbon footprint.

So, from upgrading the insulation in your walls and roof all the way to installing solar PV or thermal panels, here I’m exploring a range of both straightforward and more complicated measures to incorporate in your refurbishment project.

1. Upgrade Your Floor Insulation

If you have a suspended timber ground floor that you’re looking to update, then you can easily combine insulation as part of this project. Remove the existing floorboards and install a breathable membrane over and between the joists. Using rigid insulation, cut boards to fit snuggly between the floor joists and then re-lay your new floorboards on top to dramatically reduce draughts.

Concrete floors are literally much harder to improve. If you have sufficient ceiling height, consider a small increase in the floor level by placing a relatively thin layer of insulation over the ground floor and then adding your new floor finish over the top. As a result of the altered floor level, you would also need to change your skirting boards and adjust the height of your doors.

To improve the energy efficiency of a concrete slab itself, around 40cm-60cm depth of the material will need to be removed, which can be expensive. The floor is then replaced with a shallower concrete slab, insulation and a top screed covering.

2. Address the Wall Insulation

Internal wall insulation can work very well in some scenarios so long as you don’t lose too much space inside. To make this an effective solution, you would typically need to line out the walls by a minimum of 5cm. However, a thickness of more than 10cm would bring you closer to the standards required of a newly-built property.

If space inside your home is limited, then external insulation could be an effective solution. In this case the entire building is wrapped in insulation and new cladding applied. This will thicken your walls by at least 10cm-15cm in addition to the thickness of the cladding you select. You may need to extend the eaves of your house and move the gutters as a result. You’ll also want to consider the impact of this change upon the amount of light that will be able to come through your windows, as they’ll be more deeply recessed into your walls.

When you insulate walls it’s crucial for both your health and that of the building, that you check for risks of interstitial condensation (condensation within an enclosed wall, roof or floor cavity structure) as well as maintaining breathability. Many insulation providers will assess this for you, but you need to provide them with the exact wall make up to be accurate.

This Victorian house renovation by Bradley Van Der Straeten Architects embraces eye-catching medley of textures, colours and patterns. The walls have been lined with cork insulation and finished with a lime render to ensure the masonry structure can breathe, mitigating any damp-related issues. Elsewhere, an air source heat pump – powered by a brand-new solar pv array – generates heating and hot water for the family. Photo: French + Tye

3. Add Insulation into Your Roof Space to Reduce Energy Bills

This is usually one of the easier insulation improvements that you can make to your property. If you have an unused loft space, this can be as simple as putting down mineral wool above your ceiling joists.

To be effective, a thickness of at least 40cm of insulation is needed. If you are using the space for storage, you’ll need to make sure the new insulation isn’t squashed. Install boarding using specific stilts to avoid this.

To bring a roof space up to a habitable standard, you will need to insulate at rafter level. Usually, a layer of rigid insulation is inserted between the rafters. You need to maintain an air gap above the insulation of about 5cm between it and the roof tiles or other roofing material.

A further layer of insulation is then also fitted across the rafters, as if you are ‘boarding out’ the ceiling of the loft with insulation material. The total thickness of material needs to be around 10cm-15cm to meet new build standards and, if you can afford to do so, makes for a very efficiently insulated loft space.

4. Upgrade Doors & Windows for an Efficient Home

All building materials conduct heat differently. Glass is particularly vulnerable to heat loss. U-value calculations are needed to assess their thermal performance. Typically, a U-value of around 0.15W/m² is the standard for modern floors, walls and roofs. Efficient glazing, however, can at best achieve U-values of 0.9W/m² for triple glazing or 1.2W/m² for double glazing. So even the best window system is almost eight times worse in thermal performance than any other area of your building.

To change from double glazing to triple glazing isn’t going to make as dramatic an improvement in energy efficiency as those to any other part of your home. If you have double glazing already, you can improve the amount of air leakage around your doors and windows. Construction of a junction where a wall meets a window can be complicated and this area is likely to be covered by plasterboard internally.

As part of their listed home renovation, Mark Camillin and Liam Denny replaced the original home’s single-glazed windows with conservation double-glazed hardwood models, alongside installing heritage-style aluminium bifolds and French doors. Photo: Richard Downer

The plasterboard may be covering large gaps in the fabric of the building which have been caused by the windows not being sealed properly. I would suggest you look at these junctions and make sure that the windows are fully sealed and cavity gaps are insulated. This will mean that your home is less leaky and will be able to retain warm air inside for longer.

5. Install Ventilation Systems to Ensure a Healthy Interior

If you make insulation upgrades, you will also find that the airtightness of your home improves. Building Regulations require that background ventilation is installed in habitable spaces. Mechanical ventilation is also needed for rooms that generate higher levels of humidity or pollutants like bathrooms and kitchens.

Nowadays, most new homes will incorporate a mechanical ventilation and heat recovery (MVHR) system and it may be appropriate to install one into your existing home. The tricky part is going to be incorporating the ductwork that is usually associated with these systems. This is because a MVHR typically has a large box that controls the air handling and heat exchangers which is often located in a roof or utility space.

This extension and home renovation project by Mitchell + Corti Architects involved upgrading the property’s insulation and installing a mechanical ventilation and heat recovery system (MVHR) for optimum efficiency. Photo: Luke Weller

From here, pipes must be laid in each room so that warm waste air is collected and then drawn through the handling unit to recover its heat energy. Meanwhile, fresh cold air is drawn in from outside, warmed by the recovered heat energy and sent on to your living spaces. These pipes are usually 15cm-20cm in diameter so careful planning is needed throughout your building to stop them being obvious and unsightly.

CLOSER LOOK Quick-Fix upgrades to make

Start with the easy wins. Other measures and more major works such as insulating your walls and floors can be incorporated into a refurbishment or redecoration project. Investment in smart tech, which has now proven its worth as a reliable and effective solution, can then follow later to help you in achieving a sustainable, energy efficient home.

Lighting Start by changing your light bulbs. Modern low-energy lighting is far more efficient. You could also consider ways to get more natural light into your home by creating a light tunnel which could reduce your electricity consumption and increase your well-being.
Windows While the difference between double and triple glazing is not necessarily a noticeable one, if you have single glazing in your property (which has a U-value of 5W/m²) then upgrading this to double or triple glazed windows, will be a dramatic improvement.
Boilers If your current boiler is more than 10 years old, a simple and effective measure to consider is upgrading to a more efficient model that will reduce your energy usage.
Chimneys If you currently have an open fire with a chimney that is permanently exposed to the outside, installing a sealed flue and a low-emission woodburner, will provide you with a more efficient way of radiating the heat from burning logs back into your room.

6. Think About Switching to a Low-Carbon Heat Pump

Thoroughly insulating your home will result in a lower heating demand and so heat pumps become a viable option for your property. You can consider ground or air source heat pumps – your decision will depend upon the nature of your site and budget. Both solutions offer a great return on energy use so that for every unit of energy you put into the system, multiple units are returned.

You need to allow plenty of space for the heat pump and water storage cylinders for these systems, but once they are installed, they are very effective and efficient. You need to allow plenty of space for the heat pump and water storage cylinders for these systems. There are also hybrid options available which combine heat pumps and ventilation systems. These are ideal for smaller spaces.

CLOSER LOOK Boiler Upgrade Scheme

Aiming to increase the number of switches to heat pumps (instead of gas boilers), the government introduced the Boiler Upgrade Scheme (BUS). The BUS provides grants of up to £7,500 to encourage homeowners to replace their existing heating systems with more efficient, low-carbon alternatives. This includes air, ground and water source heat pumps and in some cases, biomass boilers.

As of the 23rd October 2023, you can access the following under the Boiler Upgrade Scheme:

£7,500 towards an air source heat pump
£7,500 towards a ground source heat pump (this includes water source heat pumps)
£5,000 towards a biomass boiler

7. Harvest the Sun’s Energy with Solar Panels

If your pitched roofs fall into a south-easterly to south-westerly orientation, you could add solar panels – either solar thermal or solar PV. Permitted development rights have recently been extended, allowing solar panels to be installed onto flat roofs, too. You’ll only require planning permission if the solar panels are being installed on the road-facing elevation or if your home is located in a conservation area/is listed.

his homeowner had solar panels installed by Eclipse Energy on both their main property and attached garage. The system, including battery storage, will generate an estimated average of 4,288kWh of electricity per year. This is over 700kWh more than the typical house in the UK consumes, with a performance warranty of 20 years

Whilst we do not have the perfect climate for solar, the technology inside the panels is improving so that they are good enough to provide you with a lot of your electrical power needs. The combined usage of solar and battery storage with an efficient electrical supplier can lower your electricity bills dramatically.

8. Take Measures to Mitigate Overheating

Much of the discussion around improving energy efficiency has tended to focus on ensuring heat retention. However, we’ve now all witnessed higher temperatures as a result of climate change. Keeping cool is a major consideration in home design, so much so that Building Regulations for new build projects have recently been updated to include measures to prevent overheating.

Large, statement windows or glazed areas have been popular architectural design features for some time now. If opting for something like this, consider your exposure to solar gains. Your project may want to incorporate external or internal solar shading devices like louvres or larger overhangs on roofs above your glazing.

This stunning barn conversion just outside Cambridge, designed by Ashworth Parkes Architects, features aluminum brise soleil solar shading on its exterior. The solution adds architectural value while controlling heat gain within the building. Photo: Michele Rossi

We have found that if you install opening rooflights at a high level, this can dramatically help cool buildings during the summer. Having higher ceilings will also help as on very hot days you will not get hot air trapped at the usual ceiling level which would have an impact on your general comfort. Measures like this can lower internal air temperatures greatly without the need to use air-conditioning which is very energy hungry and expensive.

9. Choose Natural Materials & Eco-Friendly Finishes

Specifying natural products will help keep your home chemical free. Internally, your main priority is the walls and floors. Walls must be airtight but breathable so that moisture can escape outside. If you’ve insulated with a natural product, don’t hide it behind synthetic walls. Both lime and clay plasters are a natural, breathable and flexible alternative.

There are many natural flooring products, with wood being the most popular. Make sure it is derived from a sustainable source (the FSC logo is a good indicator). If wood’s not your thing, consider cork, marmoleum or even rubber, which can all be 100 per cent natural – but always check the supply chain.

Mike Tuck Studio have transformed this typical four-bedroom Victorian terraced property with a rear extension and dormer loft conversion. Lime plaster was used on the internal walls in an unpainted paddle-brushed finish for a natural, breathable interior scheme. Photo: Luca Piffaretti

You’ll undoubtedly be using a lot of paint to decorate your home, too. Fortunately, there are plenty of green products available. Most eco-paints are water-soluble and use plant oils and resins to form the solution, with pigments coming from minerals or plant dyes.

Environmentally-friendly wood varnishes and waxes are also available, as are green options to clean and prepare walls. Sustainable wallpapers include natural coverings made from materials such as hessian, cotton and wool.

10. Install Rainwater Harvesting Systems & Recycle Water

Thousands of litres of rainwater fall on your roof each year – so why not collect it? This water can function to flush toilets, fill washing machines and water gardens.

Consider a rainwater harvesting system that collects rainfall via a drainpipe, filters out leaves and debris, and then stores the useable water in a tank. Also think about changing your toilets and showers. A low-flush toilet uses less than four litres per flush and a low-flow showerhead less than 10 litres per minute.